I’m assuming that, you’ve already expressed your dissatisfaction and distaste for the lunches she prepares and you’ve kind of been butting heads on this. It’s important to take a stand for yourself, your goals, and your choices, but to do so in a non-threatening way. Usually this is most effectively done by asking a question.
If I were you, I would pick a time when tension is low and emotions aren’t running high and ask, “Mom, can I ask why you would want me to eat food that I do not enjoy and that doesn’t work for me?”
Phrasing the question this way does two important things:
1. It puts your mom in a position to explain why she forces this food on you.
2. You are not judging the food that she is serving, only stating that it doesn’t work for you.
There is very likely some deeper reason your mom has the attitude she does regarding the lunches. Whatever the reasons she insists on a family lunch that is exactly what she serves has nothing to do with the food directly as much as it does her emotional connection and need that is filled by that experience in that way.
Knowing your mom and her family history and food history, is there some other way you can potentially propose to fill this emotional desire/need for her that will not derail your efforts to eat healthfully?
Also, one thing people who are uninterested in changing unhealthy eating habits often cannot stand is to be in the presence of someone else who is making the choices that, deep down, they know they should also be making for themselves. Even if you aren’t saying anything negative about the food she serves (and if you are, stop immediately), the fact that you are demonstrating more appropriate behavior and healthful choices around food highlights the fact she is NOT making those choices. And often people will lash out at whoever is exhibiting the wiser behavior since it prevents them from enjoying the social approval of others. This also happens a lot when one person decides not to drink in a group that is drinking a lot.
It could be that your mom is simply seeking connection time, and if you agree to join the family and enjoy the fellowship and eat none of what is served, she may come around. She ultimately will be more inclined to go along with your wishes, or at least meet you halfway, if she feels that you are respecting her choices (even if you don’t respect them, she just needs to feel that you do.)
Your health is important, but so is the health of your connections to your loved ones. It is a delicate balance sometimes, but if you show her emotional needs some respect while not allowing that to derail your physical ones, you can walk that tightrope successfully.
I wish you well.